Mark J Estienne

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The increase in serum cortisol concentrations following naloxone administration to female pigs was abolished by hypophysial stalk-transection, even though CRH and ACTH stimulated cortisol release in these animals. We suggest that the opioid antagonist enhances cortisol secretion primarily by a central action in pigs.
To determine whether endogenous glutamate and aspartate control LH secretion via N-methyl-D-aspartate (NMDA) receptors in the sheep, we evaluated the effects of the NMDA receptor antagonist D,L-2-amino-5-phosphonovaleric acid (AP5) on secretion of LH in ovariectomized lambs. Twelve lambs were ovariectomized and surgically implanted with lateral(More)
SUMMARY Although numerous extenders exist for diluting boar semen, little research has been conducted comparing commercial extenders with regard to maintaining sperm motility during storage. The objective was to use a computer assisted sperm analysis system to assess motility of boar spermatozoa were collected and sub-samples were diluted (35×10 6(More)
The objective was to determine whether treatment with 400 IU PMSG and 200 IU hCG (P.G. 600; Intervet America, Inc., Millsboro, DE, USA) at weaning improved rebreeding performance in sows that were limit-fed during lactation. Crossbred sows were allowed ad libitum access to feed or were limited to 3.2 kg of feed/day during an 18-day lactation. At weaning,(More)
groups during the fi rst thirty days of gestation. Summary Objectives: To compare pregnancy rate and number of embryos 30 days post mating in gilts group-housed in pens of three and gilts housed individually in gestation stalls. Other potential indicators of swine welfare examined included body weight, backfat thickness, lesions, lameness, display of(More)
A cooperative study comprising growth performance, bone mineralization, and nutrient balance experiments was conducted at 11 stations to determine the standardized total-tract digestible (STTD) P requirement of 20-kg pigs using broken-line regression analysis. Monocalcium phosphate and limestone were added to a corn-soybean meal-based diet at the expense of(More)
Objective: To assess hydrated sodium calcium aluminosilicates (HSCAS) and an antioxidant supplying ethoxyquin and tertiary butyl hydroquinone (TBHQ) as dietary additives to mitigate physiological effects of aflatoxin in feed for pigs. Materials and methods: Ninety pigs (9.42 ± 0.05 kg) were used in a study with five dietary treatments: an uncontami-nated(More)
The objective was to determine the effects of the opioid peptide receptor antagonist, naloxone on circulating concentrations of luteinizing hormone (LH) and testosterone in boars characterized as having high (n=8) or low libido (n=8) based on the willingness to mount an artificial sow and allow semen collection. On the day of the experiment, blood was(More)
Experiments were conducted investigating the effects of prostaglandins and prostaglandin synthesis inhibitors on libido in boars. In Experiment 1, two prostaglandin products were compared with regard to expediting the training of boars for semen collection. On each of five consecutive days, boars received i.m. treatment with saline, dinoprost tromethamine(More)
The main objective of this study was to determine the effects of dietary supplementation with omega-3 polyunsaturated fatty acids on ovulation rate and litter size at day 27 post-mating in gilts. Estrous cycles were synchronized in crossbred gilts (n=48) using a progestin (Matrix; Intervet America Inc., Millsboro, DE, USA), fed at a rate of 15 mg/day for 18(More)